I have a vacuum leak (on the lock circuit) that I think I have traced to the master door lock vacuum switch in the driver's door. No leaks downstream connector along floor at driver's door. Leaked upstream so I removed driver's door panel and disconnected the lock circuit hard line (red stripe) thinking I had a crack in the hard line between door and body (rubber tube is shot) but it held vacuum. When I tested it reconnected to master switch I could hear air escaping and assume that means switch is leaking and needs replacing.

Then I read in other threads where it was that the switch vented and hearing a hissing noise is normal. So now I am confused.

Is there a different procedure for checking the switch?

Thanks